Growth and purification of Herpesvirus saimiri (HVS) using established methods; development of methods for obtaining large amounts of defective genomes; isolation of HVS DNA and assay of its transforming potential, using isolated lymphatic primate cells; isolation of episomal DNA from tumor cell lines and biopsy materials; mapping of episomal DNA including electrophoresis, "blotting", reassociation kinetics, and electron microscopy.